The invention relates to a packaging container made from a cold formed composite, a process for its manufacture and the use thereof.
1. Field of the Invention
It is known to employ packaging means for the purpose of protecting, e.g., pharmaceutical products, medical aids, diagnostic aids and other products which are sensitive to light, gas and/or moisture. Particularly suitable types of packaging are shaped forms of packaging made by stretching, stretch drawing, or deepening. In order to make packaging impermeable to light, gas and vapors, the material from which the packaging is made must have a barrier layer. A particularly suitable barrier layer may be, e.g., a metal foil or metal strip. In practice, as the metal foil alone is not able to fulfill all of the requirements made of a packaging material, further layersxe2x80x94in particular layers of plasticxe2x80x94are applied to one or both sides of the metal foil. Such layers may, e.g., be extrusion bonded or layers in the form of films of thermoplastics attached by means of adhesive agents. With such multilayer laminates readily formable packaging materials are produced that can be processed further, e.g., into the base parts of blister packs or other forms of packaging.
It has now been found that none of the laminates which have found use in practice exhibit sufficient flatness and/or stiffness for further processing after being shaped into packaging forms or parts such as the base part of packaging. It has also been found that laminates which exhibit inadequate flatness and/or stiffness, after shaping into parts for packaging such as base parts for blister packs or push-through packs, result in shaped parts that also exhibit inadequate flatness and/or stiffness. By flatness is meant here that the laminate exhibits a tendency to roll or parts formed out of the laminate are domed and e.g. do not lie uniformly on a flat surface, but instead are curved in a wavy, arched or dome-like manner.
2. Broad Description of the Invention
The object of the present invention is therefore to propose a packaging container which is manufactured out of a composite and the packaging container exhibits a high degree of flatness and/or stiffness.
That objective is achieved by way of the invention in that the composite from which the packaging container or parts thereof is/are manufactured exhibits a layered structure containing:
a) a plastic film having a thickness of 10 xcexcm to 250 xcexcm,
b) a biaxially or uniaxially stretched film of the polyvinylchloride, polyolefin, polyamide or polyester type having a thickness of 10 to 100 xcexcm, or a biaxially or uniaxially stretched plastic laminate of two films of the polyvinylchloride, polyolefin, polyamide or polyester type each having a thickness of 10 to 50 xcexcm,
c) a metal foil having a thickness of 20 to 200 xcexcm, and
a1) a plastic film having a thickness of 10 to 250 xcexcm,
and the packaging container exhibits a high degree of flatness and/or stiffness.
Usefully, according to the present invention packaging containers, or parts thereof, exhibit a laminate which features between layer
c), the metal foil having a thickness of 20 to 200 xcexcm, and
a1) the plastic film having a thickness of 10 to 250 xcexcm,
a layer
b1) a biaxially or uniaxially stretched film of the polyvinylchloride, polyolefin, polyamide or polyester type having a thickness of 10 to 100 xcexcm, or a biaxially or uniaxially stretched plastic laminate of two films of the polyvinylchloride, polyolefin, polyamide or polyester type each having a thickness of 10 to 50 xcexcm.
In practice layer a) is on the side of the container facing outwards, while layer a1) forms the side of the container facing inwards i.e. the inner face.
The plastic films a) and a1) may e.g. be of thermoplastics such as halogen-containing polymers, polyesters, polyolefins, polyamides or acrylnitrile copolymers. The plastic films a) and a1) may preferably be non-stretched or if desired uniaxially or biaxially stretched.
The layers b) and b1) are biaxially or uniaxially stretched plastic films. Usefully, the plastic films b) and b1) are of the uniaxially stretched polyvinylchloride or uniaxially or biaxially stretched polyamide, polypropylene and polyester film type or laminates.
Examples of plastics a), b), a1) and b1) based on halogen-containing polymers are polymers of vinylchloride (PVC) and vinyl plastics, containing vinylchloride units in their structure, such as copolymers of vinylchloride and vinylesters of aliphatic acids, copolymers of vinylchloride and esters of acrylic or methacrylic acids or acrylnitrile, copolymers of diene compounds and unsaturated dicarboxyl acids or their anhydrides, copolymers of vinylchloride and vinylchloride with unsaturated aldehydes, ketones etc. or polymers and copolymers of vinylidenchloride with vinylchloride or other polymerizable compounds. The vinyl-based thermoplastics may also be made soft in a conventional manner by means of primary or secondary softeners. Films out of PVC may in some cases also be uniaxially (oPVC) or biaxially stretched.
If the plastic films a), b), a1), and b1) are of polyesters (PET-films), then examples of the polyesters are polyalkylene-terephthalate or polyalkylene-isophthalate with alkylene groups or radicals with 2 to 10 carbon atoms or alkylene groups with 2 to 10 C atoms interrupted by at least one xe2x80x94Oxe2x80x94 atom, such as, polyethylene-terephthalate, polypropylene-terephthalate, polybutylene-terephthalate (polytetramethylene-terephthalate), polydecamethylene-terephthalate, poly-1,4-cyclohexyldimethylol-terephthalate or polyethylene-2,6-naphthalene-dicarboxylate or mixed polymers of polyalkylene-terephthalate and polyalkylene-isophthalate, where the fraction of isophthalate amount, e.g., to 1 to 10 mol. %, mixed polymers and terpolymers, also block polymers and grafted modifications of the above mentioned materials. Preferred are polyethylene-terephthalate films. Other useful polyesters are known in the field by the abbreviation PEN.
Other polyesters are copolymers of terephthalic acid and a further polycarboxyl acid with at least one glycol. Useful thereby are the copolymers of terephthalic acid, ethyleneglycol and an additional glycol. Preferred are glycol-modified polyesters known in the field as PETG.
Useful polyesters are polyalkylene-terephthalates with alkylene groups or radicals with 2 to 10 carbon atoms and polyalkylene-terephthalates with alkylene groups or radicals with 2 to 10 carbon atoms which are interrupted by one or two xe2x80x94Oxe2x80x94 atoms.
Further preferred polyesters are polyalkylene-terephthalates with alkylene groups or radicals with 2 to 4 carbon atoms and, very highly preferred, polyethyleneterephthalates belonging to which are also A-PET, PETP and the above mentioned PETG or G-PET.
Examples of polyolefins for plastic films a), b), a1) and/or b1) are polyethylenes (PE) e.g. high density polyethylene (HDPE, density larger than 0.944 g/cm3, medium density polyethylene (MDPE, density 0.926-0.940 g/cm3), linear polyethylene of medium density (LMDPE, density 0.926.0.940 g/cm3), low density polyethylene (LDPE, density 0.910-0.925 g/cm3) and linear low density polyethylene (LLDPE, density 0.916-0.925 g/cm3), for example as non oriented (PE film) or uniaxially or biaxially oriented films, (oPE film), polypropylenes (PP), such as axially or biaxially oriented polypropylene (oPP film) or cast polypropylene (cPP film), amorphous or crystalline polypropylene or mixtures thereof, ataktic or isotaktic polypropylene or mixtures thereof, poly-1-butene, poly-3-methylbutene, poly-4-methylpententene and copolymers thereof, then polyethylene with vinylacetate, vinylalcohol, acrylic acid etc. such as e.g. ionomeric resins, such as copolymers of ethylene with 11% acrylic acid, methacrylic acid, acrylic esters, tetrafluorethylene or polypropylene, also statistical copolymers, block polymers or olefin polymer-elastomer mixtures. Preferred are high density polyethylenes and polypropylenes, also ionomers, e.g. known under the trade names Surlyn, and ethylene-acrylic acid copolymers (EAA).
If the plastic films a), b), a1) and b1) are polyamide films (PA) then e.g. the following belong to the polyamides viz., polyamide 6, a homo-polymer of xcex5-caprolactam (polycaprolactam); polyamide 11, polyamide 12, a homo-polymer of xcfx89-laurinlactam (polylaurinlactam); polyamide 6.6, a homo-polycondensate of hexamethylenediamine and adipinic acid (poly-hexa-methylene-adi-amide); polyamide 6.10, a homo-polycondensate of hexa-methylene-diamine and sebacinic acid (poly-hexa-methylene-sebacamide); polyamide 6.12, a homo-polycondensate of hexa-methylene-diamine and dodecandic acid (poly-hexa-methylene-dodecanamide) or polyamide 6-3-T, a homo-polycondensate of trimethyl-hexa-methylene-diamine and terephthalic acid (poly-trimethyl-hexa-methylene-terephthalic-amide), and mixtures thereof. Films of polyamide may in some cases be uniaxially or biaxially stretched (oPA).
If the plastic films a), b), a1) and b1) are of acrylnitrile-copolymers, then e.g. the following are included in this group viz., copolymers of acrylnitrile or methacrylnitrile with acrylic acid esters, vinyl-carboxylate esters, vinyl halides, aromatic vinyl compounds or unsaturated carboxylic acid and diene and in particular acrylnitrile-methylacrylate copolymers (e.g. known under the trade name xe2x80x9cBAREXxe2x80x9d.
If the above mentioned plastics are extrudable, then they may also be applied to the laminate in the form of an extruded layer.
Layer c), a metal foil, has a thickness of 20 to 200 xcexcm, a thickness of 20 to 150 xcexcm being useful and 30 to 60 xcexcm being preferred. The metal foil may be of iron, steel, nickel, copper, tin, bronze, brass, aluminum, etc. The metal foil is advantageously of aluminum having a purity of 99.95% to 97% (wt. %), the remainder being the unavoidable accompanying impurities or alloying elements. Examples of alloys are those having aluminum as the main constituent and the alloying element Fe; Si; Mg; Ti and/or Cu.
The layers a), and a1), i.e. the uniaxially or biaxially stretched films of plastics of the polyvinylchloride, polyolefin, polyamide or polytethyleneterephthalate type may usefully have thickness of 10 to 80 xcexcm and advantageously a thickness of 12 to 50 xcexcm. For plastic laminates the stated dimensions refer to the total thickness.
In order to join the described layers to each other, i.e., a) to b), b) to c), c) to a1) or c to b1) and b1) to a1), these may be adhered to each other by adhesives such as laminate coatings, laminate adhesives and/or adhesive agents and if desired by precoating with bonding materials, by hot calendering, by extrusion coating, by coextrusion coating or by means of a combination of these methods to form composites, laminates or films.
Suitable laminate adhesives may contain solvents, be solvent-free, or may be aqueous acrylic adhesives or polyurethane adhesive systems. Adhesives which harden under the influence of electromagnetic rays (e.g. UV; electron beams) may, however, also be employed.
Preferred are polyurethane-based laminate adhesives.
For example, di-isocyanate or aliphatic polyesters may be employed as bonding agents. As a rule these bonding agents are only employed between the outwards facing layers.
Suitable coatings are e.g. those based on acrylates, epoxy resins, melaminic resins, uric resins, polyurethanes, cellulose nitrate, polyesters and mixtures thereof. The coatings may e.g. be solvent-based or water-based, or may be single, two or more component systems. The coatings are hardenable e.g. by drying, by application of heat, chemical means and/or by radiation (UV; electron-beams; IR).
Usefully, the thickness of coating materials employed between the individual layers of the composite for the packaging container according to the invention is 0.1 xcexcm to 12 xcexcm.
The laminate adhesive may e.g. be employed in amounts of 1 to 10 g/m2, preferably from 2 to 8 g/m2 and in particular in an amount of 3 to 6 g/m2. The laminate adhesives may also be employed in such amounts that the layers have a thickness of at least 0.1 xcexcm and at most 12 xcexcm.
The metal surface may by appropriate pretreatment (e.g., brushing, chromate treatment, ionizing, ozone, corona, flame or plasma treatment) exhibit better bonding for the adhesive or coating or for an extruded layer. To assist and improve the bonding of the coatings, bonding agents or laminate adhesives between the plastic films or extruded layers, it is often useful to provide the films on the sides facing the adhesive or the bonding of extruded layers with adequate surface tension. Increasing the surface tension may be effected preferably by an ionizing, ozone, plasma, flame or corona pretreatment.
The bonding of the individual layers of the laminate may also be obtained by extrusion laminating or hot calendering. The packaging containers may exhibit on their inner side, i.e., on the side facing the contents, in some cases also on their outer side, a sealing layer such as a sealing film or sealing coating. The sealing films or sealing coatings may, e.g., contain or be of polyolefins. The sealing layer makes it possible to apply a lid to the container according to the invention. Such lids may, e.g., be lid foils, which are sealed to the shoulder of the container. Suitable lid foils may contain a metal foil such as an aluminum foil and, plastic films and/or coatings may be applied to one or both sides of the metal foil. On at least one side of the lidding foil there may be an outermost layer in the form of a sealing layer via which the lidding foil may be joined to the packaging container.
On the inner side and/or outer side or directed towards the inner and/or outer side, in each case with reference to the container according to the invention, may be the composite coating and/or printed pattern.
For example, the outer lying and/or the inner lying film of the laminate may exhibit a reversed image pattern on its inner side i.e. facing the composite. A reversed image pattern is particularly suitable for transparent and translucent films.
It is also possible to provide the outer lying and/or the inner lying film with a printed pattern and as required to cover the pattern with a coating. The outer and/or the inner lying side of the composite may also be provided with a coating, whereby as required the coating may also be printed on and/or patterned on the packaging line e.g. by means of UV, solvent or by laser or electron beams.
It is also possible to provide coating layersxe2x80x94which may also be coloredxe2x80x94between the other layers than the outer and inner layers and the next innermost layer. The films employed or the extruded layers may be transparent, translucent or opaque and may be clear or may be wholly or partially colored.
Typical examples of packaging containers according to the invention are laminates having a layer c) of aluminum foil or thin strip of thickness 20 to 150 xcexcm and a layer b) in the form of a biaxially or uniaxially stretched film or a composite of two films of the polyvinylchloride, polypropylene, polyamide or polyester type having a thickness of 10 to 100 xcexcm, whereby the layer b) covers one of the two surfaces of layer c). Both layers b) and c) are to advantage a PVC film with a thickness of 30 to 100 xcexcm or a PET film of thickness 12 to 200 xcexcm or a PET film of thickness 15 to 200 xcexcm or a cPP film of thickness 20 to 200 xcexcm or a PP film of thickness 30 to 60 xcexcm. On the free side of layer c) of this part of a composite are further layers described below.
In a first specific embodiment the above mentioned partial composite may exhibit on the still free side of layer c) the layer a1), preferably a PVC film of thickness 30 to 150 xcexcm, a PET film of thickness 12 to 200 xcexcm, a PE film of thickness 30 to 60 xcexcm, a PP film of thickness 30 to 60 xcexcm, a cPP film of thickness 20 to 200 xcexcm, an ionomer layer with ethylene acrylic acid (EAA), e.g. a Surlyn layer of 10 to 100 g/m2 (ca. 11 to 110 xcexcm), or an extruded polyolefin layer of thickness 20 to 200 xcexcm.
In a second specific embodiment the above mentioned partial composite may have applied to its still free layer c) e.g. a layer b1), an oPA film of thickness 15 to 25 xcexcm or a PET film, in particular a PEN film, of thickness 12 to 50 xcexcm or an oPVC film of thickness 40 to 100 xcexcm and on top of a layer of bonding agent the layer a1), a PE film of thickness 15 to 100 xcexcm or a PP film of thickness 30 to 60 xcexcm or a cPP film of thickness 20 to 100 xcexcm or a PET film of thickness 12 to 200 xcexcm or a PVC film of thickness 30 to 150 xcexcm may be applied.
Preferred examples of packaging containers according to the invention exhibit composites with a layer structure containing
where the numbers are the thickness of the layers in xcexcm and PVC stands for polyvinylchloride, oPVC for uniaxially oriented polyvinylchloride, PP for polypropylene, PET for polyethylene-terephthalate, PE for polyethylene, oPA for oriented polyamide, PEN for polyester of the PEN type, Al for aluminium foil, oPP for oriented polypropylene and PP for polypropylene.